Virtual reality head mounted displays (HMDs) are becoming increasingly popular, and the applications that implement virtual reality, beyond the traditional gaming systems, are likewise increasing. In practically all instances, the different types of HMD function in a manner similar to 3D goggles in that the HMD displays an image to each eye. The images may be generated in such a fashion as to cause the wearer of the HMD to perceive a 3D environment.
The goal is to present a world that appears realistic and behaves like the real world. Generally, HMDs also contain tracking hardware to determine a position and orientation of the HMD so that the images may be adjusted for the position and orientation. As such, the wearer may “look around” and have the images adjust according to the position and orientation (i.e., direction) of the gaze of the wearer.
Current HMDs present the images directly into the eyes of the wearers. Different mechanisms have been developed to accomplish this, including positioning a display in front of the eyes of the wearer, positioning a projector in front of the eyes of the wearer, or using mirrors or prisms in front of the eyes of the wearer. Each of these examples, and many others not mentioned, suffers from the same issue, in that positioning display or projection hardware out in front of the wearers face increases the weight of the HMD, and decreases the comfort of the wearer. If the goal is to immerse a user in a virtual world, wearing heavy equipment suspended in front of the wearers eyes distracts the user from the virtual world.